Manufacture of incandescent electric lamps



(No Model.)

T. A. EDISON. MANUFACTURE OF INOANDESGENT ELECTRIC LAMPS. No 411,018.Patented Sept. 17, 1889.

UNITED STATES PATENT OFFICE.

THOMAS A. EDISON, OF LLEWELLYN PARK, NEW JERSEY.

MANUFACTURE OF INCANDESCENT ELECTRIC LAMPS.

SPECIFICATION forming part of Letters Patent No. 411,018, datedSeptember 17, 1889. Application filed July 17, 1886. Serial No. 208 242.(No model.)

T 0 aZZ whom it may concern.-

Be it known that I, THOMAS A. EDISON, of Llewellyn Park, in the countyof Essex and State of New Jersey, have invented a new and usefulImprovement in Processes of Manufacturin g Incandescent Electric Lamps,(Case No. 666,) of which the following is a specification. The object ofmy invention is to simplify the process of exhausting the globes ofincandescent electric lamps and to do away with danger of injur Y to thefilament, which has sometimes occurred in the process heretoforefollowed.

Ilei'etofol'e the lamp to be exhausted has been placed in connectionwith a Sprengel vacuum-pump, and during the operation of such pump thecarbon filament has been heated to high incandescence by the passage ofan electric current, the object of such heating being to expel from thecarbon certain gases and vapors which were supposed to be occluded orcontained in the pores of the carbon, such gases and vapors being thenwithdrawn by the pump. I have discovered that the amount of gases andvapors contained in the pores of the filament is so small as to be ofpractically no consequence in impairing the vacuum within the globe, andthat the gases and Vapors which were drawn off from the lamp by theheating of the filament came not from the filament, but in fact from theinner surface of the globe, to the glass of which they adhered untildrawn off by heat. It was thus necessary to bring the filament up to avery high incandescencehigher than that at which it was intended to beusedin order to sufficiently heat the glass to driveoff the adheringfluids. This high incandescence was of course in some cases dangerous tothe filament, and also diminished the life of the lamp in use. By myinvention I do away with this heating of the filament, 4 and so avoidthese dangers, and also do away with the expense and inconvenience ofproviding the power required to produce the current necessary for suchheating.

My invention consists in heating the globe from an external sourceduring the process of exhaustion. This heating may be accomplished invarious ways. A convenient apparatus for the purpose is shown in theaecompanying drawing.

A is a Sprengel vacuum-pump, to which the incandescent electric lamp Bisattached in the usual manner.

C is a receptacle containing phosphoric anhydride or other absorbent ofmoisture.

D is a heating-lamp burning oil or alcohol. From its chimney a metaltube or chamberE extends, which surrounds the electric lamp B, such tubehaving a hole for the exhausttube of the lamp. Through this tube theheat from the flame passes up around the electric-lamp globe, and suchglobe is thereby heated until the adhering gases and vapors are driven01f from the glass and are withdrawn through the pump or absorbed by thesubstance in bulb (J.

After the lamp is exhausted it is sealed off at a, and is then ready foruse.

Vhat I claim is 1. Theherein-described process of manufacturingincandescent electric lamps, consisting in externally heating thelamp-globe during the process of exhaustion.

2. The herein-described process of manufacturing incandescent electriclamps, consisting in exhausting the globe bya Sprengel vacuum-pump andat the same time heating such globe externally.

3. The herein-described process of manufacturing incandescent electriclamps, consisting in heating the lam p-globe by a current of heated airor gas during the process of exhaustion.

This specification signed. and witnessed this 15th day of July, 1886.

THOS. A. EDISON.

Witnesses:

WM. PELZER, A. W. KIDDLE.

